Tooth and Nail takes place in a post-apocalyptic world that was not the result of a nuclear catastrophe, viral outbreak or cataclysmic collision with a rock from outer space. As we learn from Darwin (Robert Carradine), the leader of a group that's trying to build a new life for themselves, the world simply ran out of gas, which brought an end to transportation, electricity, nuclear power and, before long, civilization as we know it.

Avoiding the mad rush to the south that's steering the hopes of many survivors, Darwin and his followers have decided to hang back in Philadelphia, where they occupy an abandoned hospital that offers both clean water and a hell of a lot of space . While out scouring the streets for something useful, three of the group, including Viper (Michael Kelly) and Ford (Rider Strong), happen upon an assault in progress. After chasing off the would-be killer (Vinnie Jones), they offer assistance to one of his potential victims, a young girl named Neon (Rachel Miner), and invite her into their fold. But Neon's arrival comes with a price: a rag-tag band of cannibals called the Rovers have been following her, and have now tracked her to the hospital. Preying upon the living in their quest for food, the Rovers surround the facility, trapping the remaining survivors inside. With the promise of nightly attacks looming over them, the group must come up with a plan to keep themselves from becoming the Rovers next main course.

Prior to the action, Tooth and Nail creates an interesting post-apocalyptic reality, and the various personalities that make up Darwin's group (the restlessness of Michael Kelly's Viper, the loyalty of Nicole DuPort's Dakota) is a nice bit of storytelling to carry us through to the first on-screen kill, which is simultaneously gruesome and shocking (one character meets their end by way of a meat cleaver to the throat). Another of their number, named Victoria (Beverly Hynds), had disappeared the day before without a trace, and when the rest of them find a pool of blood on the floor (the remnants of the fresh cleaver kill), it kicks off a mystery that nearly rips their tight-knit community apart. But the truth doesn't stay a mystery for long: Michael Madsen, playing one of the Rovers, makes the kind of entrance only Michael Madsen can make, burying an axe into the back of another of Darwin's followers while whistling “I've Been Working on the Railroad”. The Rovers, with their Mad Max attire and no-nonsense approach to murder, remain an enigma through much of the film, but that doesn't mean they're any less menacing.

Tooth and Nail shifts nicely from a story of survival to a battle for survival, painting a picture of a world that, though nearly devoid of human life, still hides a few dangers up its sleeve.